MOSCOW — A human-rights activist in Chechnya has been detained by the police on drug possession charges in a case that colleagues and international observers say is part of a concerted effort to drive dissidents out of the Russian republic.

The activist, Oyub Titiev, 60, has run the Chechen branch of the Memorial Human Rights Center since the 2009 abduction and murder of another activist, Natalya Estemirova, a case that remains unsolved.

Chechnya’s Ministry of Internal Affairs reported on its website that the police found a plastic bag with what it said the police suspected was marijuana weighing about 180 grams when they stopped Mr. Titiev’s car for a document inspection on Tuesday. The drug possession offense is punishable by up to 10 years in prison.

The State Department on Wednesday called for the immediate release of Mr. Titiev, saying his detention was “the latest in a string of reports of alarming recent human rights violations in Chechnya.”

Nils Muiznieks, the Council of Europe’s commissioner for human rights, said that Mr. Titiev had made an “invaluable contribution over many years” and that the case was based on “dubious charges that lack credibility.”

Chechnya, in the North Caucasus, is run by the strongman Ramzan Kadyrov. His father, Akhmad, had fought against Russia during the first Chechen war in the mid-1990s but later allied with President Vladimir V. Putin, who appointed him in 2000 to run the region. The elder Kadyrov was assassinated in 2004.

Mr. Kadyrov’s Facebook and Instagram accounts were recently deactivated because he had been added to a United States sanctions list. Mr. Kadyrov has reportedly been involved in torture, kidnapping and murder, as well as other human rights abuses.

Tanya Lokshina, the Russia program director for Human Rights Watch, said in a statement that fabricated drug charges were being used by the authorities to rid Chechnya of people who question Mr. Kadyrov’s rule.

“Framing people for drug crimes has become an increasingly frequent tactic,” she wrote.

In 2014, Ruslan Kutaev, a politician and activist, was sentenced to four years in prison on heroin possession charges after disobeying Mr. Kadyrov’s orders not to hold a conference marking the 70th anniversary of the deportation of Chechen and Ingush people under the Soviet dictator Joseph Stalin. He was released late last year.

Zhalaudi Geriev, a journalist with the Caucasian Knot news website, which is critical of Mr. Kadyrov, was sentenced to three years in prison on marijuana possession charges in 2016.

Human Rights Watch said that both men were tortured in police custody.